High-power transistor, such as microwave transistors, are available with power levels up to about 1000 watts at radio frequencies, decreasing to less than about 100 watts at higher microwave frequencies. For applications requiring a much greater power level than the power level of a single high-power transistor, the outputs of a number of high-power transistors needs to be coherently combined.
One conventional system to combine the outputs of a number of high-power transistors relies on building many individual amplifier modules, each with a single transistor, and then combining the outputs of the amplifier modules using a microwave power combiner. Such a conventional system typically requires a set of microwave cables, electrical power cables and cooling lines for each module. For a high-power solid-state amplifier with many modules this may represent a significant complexity which may increase costs and potentially decreases reliability. Moreover, in the event of a failure of one or more of the modules or transistors, the conventional system is typically turned off and the defective high-power transistor or amplifier module must be replaced.